Black water spews onto roof when heating turned off

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niallo34

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I have GFCH in a semi-d approx thirty years old.

There is a small black hose (about six inches in length) sticking out of the back of the house and when I turn off the heat, this spews out black water for about a 30 seconds to a minute - it overhangs the extension and comes onto the windows in the extension ceiling.

It's quite powerful as forceful as a hose turned up full.

I assume the black liquid is from the radiators as they creak and make noise when the heat goes off.

Anyone know how I can prevent this from happening??
 
Sounds like the overflow hose, check the ballcock of the tank in your attic - is it sticking?. Don't know the relationship with the heating I'm afraid.
 
Niallo34
I'd suggest that you are running a serious risk of flooding the house with this black stuff - the hose you are referring to is your last line of defence when something serious has gone wrong with the system.
 
niallo34 said:
I have GFCH in a semi-d approx thirty years old.

There is a small black hose (about six inches in length) sticking out of the back of the house and when I turn off the heat, this spews out black water for about a 30 seconds to a minute - it overhangs the extension and comes onto the windows in the extension ceiling.

It's quite powerful as forceful as a hose turned up full.

I assume the black liquid is from the radiators as they creak and make noise when the heat goes off.

Anyone know how I can prevent this from happening??
Click to expand...


The pipe is an overflow from your expansion tank. When the heating is on a pump pumps water around system and the heating water expands.

In your case it sounds like water is being pumped up the expansion pipe into tank and it quickly over fills, hence the water coming out of over flow pipe.

Is this a new thing? or have you had work done recently? like a new pump fitted for example.
Have you had to shut down water recently? Has anyone touched valves in the hotpress?

Letting this continue is a bad idea as everytime it happens it introduces oxygen into system which encourages corrosion
 
I'm not sure how long it's been happening, but we moved in in late May and only turned the heat on for the first time in October, so it could well be happening years.

A plumber told me yesterday to locate the feed into the boiler and to check that the valve is closed and secure

He also advised putting Fernox into the heating system.

There has been no changes to anything that I'm aware of.

Thanks..
 
Do you have motorised valves controlling the heat to different areas of the house?
 
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